BCC? any other way?

R

RJS22

New Member
Aug 18, 2009
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0
0
Ellicott City, MD
so i was having terrible 1j ecu issues and decided to go 2j ecu and now run into the issue of not being able to run more than 14psi. and i am having a terrible time trying to find a Greddy BCC due to it being discontinued...any other options? anyone kno a DIY for it?

thanks!
 
JPsToyota

JPsToyota

Member
Sep 17, 2008
231
0
16
East-Central, FL
You need to clamp the voltage output signal from the MAP sensor to the ECU. If you put a meter on it and then pressurize the MAP sensor inlet (gently), you will see the voltage climb and fall in relation to pressure, this is how the MAP sensor relays the air input information to the ECU. I don't remember wire colors, you will just have to test the wires for the correct voltage. I assume the correct one will be around 1.5 to 3 volts at atmospheric pressure (no pressure added).

Well, the ECU has a fail-safe, I guess in case of a wastegate failure type thing, that when this output voltage reaches a certain point it hits "boost-cut". You need to "clamp" this voltage so it still moves freely and accurately throughout the sensor range (so you still get accurate readings to the ECU, so no scaling voltage modifications) but limits right before the "boost-cut" voltage point.

And that's why God made Zener diodes.
 
R

RJS22

New Member
Aug 18, 2009
39
0
0
Ellicott City, MD
so basically wire in a zener diode in w/e wire that may be that is limiting it?

any idea which diode im looking for? radioshack has 2 zener's that i saw, a 5.1v and a 12v..?
 
JPsToyota

JPsToyota

Member
Sep 17, 2008
231
0
16
East-Central, FL
You might have to play around with the diodes and do some research on making a circuit. There is information about this topic around the internet. The zener setup will go in the signal wire from the MAP like I explained, that is the signal that sends the ECU into "boost-cut".

I know people made full circuits with resistors, I tried a straight wired zener diode in my application and it worked fine in testing and driving. I can't really remember alot of the specifics, I know I went online and bought a range of zener diodes from like 3.9V-6.XV, I ended up having to use a higher "rated" voltage than actual voltage. It was in the mid 5V range rated IIRC and I was looking for somewhere around 4.2-4.5V clamp, I can't remember the exact boost cut voltage for the Aristo ECU I had. It might be different for your ECU anyway.

It's just going to be research, testing and trial and error for awhile. That's the price you have to pay for saving money on a Greddy BCC.
 
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